From patchwork Fri Sep 10 08:26:42 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: =?utf-8?q?Christian_K=C3=B6nig?= X-Patchwork-Id: 509330 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-15.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A7261C433F5 for ; Fri, 10 Sep 2021 08:27:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 88689610C7 for ; Fri, 10 Sep 2021 08:27:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231731AbhIJI2K (ORCPT ); Fri, 10 Sep 2021 04:28:10 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60726 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231502AbhIJI2J (ORCPT ); Fri, 10 Sep 2021 04:28:09 -0400 Received: from mail-wm1-x32a.google.com (mail-wm1-x32a.google.com [IPv6:2a00:1450:4864:20::32a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D5C00C061574 for ; Fri, 10 Sep 2021 01:26:58 -0700 (PDT) Received: by mail-wm1-x32a.google.com with SMTP id z9-20020a7bc149000000b002e8861aff59so855654wmi.0 for ; Fri, 10 Sep 2021 01:26:58 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=Qg7l/EFf9rR8AshzqDpvjOG0up4Bpj2cOJ4DPctGlsg=; b=hYO0/QJu51bK9PIC7tiV1/qT5E7pqxEhAMyFhTjajOMeAp5BV6wFpmpNanNfoAaT1i ryloc9aWQdHyMvzcBh2C/v5qQSV4OPVUQQBkhxNiXROJRTgT7YjJMFopK1+/73HgYCm/ 4BirXEKTsHk/iST/yzgyCagZPytlnvADiEELvSqKk4lxJk1GkExVa7NRcNo9JUvY8zKL gXi9cBGqGU6XRIW02kDuaxAeUBHrDd44Az/AwFmPs99Qiznj/K9eXesRP8/FYh4j71FX 1wTIDFEtHgZa0OHrGKN4S+kMzO3Re+APPHn3MqQVpFrVz/hdsxhKAXijO6UUy5x1jOSE uQwQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=Qg7l/EFf9rR8AshzqDpvjOG0up4Bpj2cOJ4DPctGlsg=; b=PRCXYMvrJd7jaRegMAhB+miL5tZ6mVnB66dpbiP1cTzsC2LWBNNHrWWLAoniRLjC4t dc1L+aPFc4uIv8cMc0csAZeqDDQexdKiNLOT5MLJsa1mYQKqctwOTasCA+H0uyUhW1xa 0KfQQMNZEJNHIos+IicJns/eT39jN2Mkgk54GhRTrUP9bZuCriHhvtPFGEVFk0Us5hEE jtNVL68WtBsGAbd8usdEsEcT+L+yGykGDMdNn0+73vW0c8AVwvQVRlwNFaA2g8sK5rLP bj4oU03Nn/38LT8064tiX5O0Wc5eBPwxXREl6nsHMuSYg/QppLxLq1DXtwM4CUKOLzeG qy2A== X-Gm-Message-State: AOAM531Ad4m9Lb2hZZR5axo1a2+aTmCd3p41zu/2tU+8FwqTYxednQNP B3N4veC0sbRVj4VxcL+OIt0= X-Google-Smtp-Source: ABdhPJxY8uiFmE1WR/yWgIv+FQO7at7p+ltamy2XMb+pMdNS7j34icDOhYn2bnvmsAmeZ9nekC359A== X-Received: by 2002:a1c:f314:: with SMTP id q20mr6966890wmq.154.1631262417454; Fri, 10 Sep 2021 01:26:57 -0700 (PDT) Received: from abel.fritz.box (p5b0ea1b5.dip0.t-ipconnect.de. [91.14.161.181]) by smtp.gmail.com with ESMTPSA id l10sm4429756wrg.50.2021.09.10.01.26.56 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 10 Sep 2021 01:26:57 -0700 (PDT) From: "=?UTF-8?q?Christian=20K=C3=B6nig?=" X-Google-Original-From: =?utf-8?q?Christian_K=C3=B6nig?= To: linaro-mm-sig@lists.linaro.org, dri-devel@lists.freedesktop.org, linux-media@vger.kernel.org Cc: daniel@ffwll.ch Subject: [PATCH 01/14] dma-buf: add dma_resv_for_each_fence_unlocked Date: Fri, 10 Sep 2021 10:26:42 +0200 Message-Id: <20210910082655.82168-1-christian.koenig@amd.com> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-media@vger.kernel.org Abstract the complexity of iterating over all the fences in a dma_resv object. The new loop handles the whole RCU and retry dance and returns only fences where we can be sure we grabbed the right one. Signed-off-by: Christian König --- drivers/dma-buf/dma-resv.c | 63 ++++++++++++++++++++++++++++++++++++++ include/linux/dma-resv.h | 36 ++++++++++++++++++++++ 2 files changed, 99 insertions(+) diff --git a/drivers/dma-buf/dma-resv.c b/drivers/dma-buf/dma-resv.c index 84fbe60629e3..213a9b7251ca 100644 --- a/drivers/dma-buf/dma-resv.c +++ b/drivers/dma-buf/dma-resv.c @@ -323,6 +323,69 @@ void dma_resv_add_excl_fence(struct dma_resv *obj, struct dma_fence *fence) } EXPORT_SYMBOL(dma_resv_add_excl_fence); +/** + * dma_resv_walk_unlocked - walk over fences in a dma_resv obj + * @obj: the dma_resv object + * @cursor: cursor to record the current position + * @all_fences: true returns also the shared fences + * @first: if we should start over + * + * Return all the fences in the dma_resv object which are not yet signaled. + * The returned fence has an extra local reference so will stay alive. + * If a concurrent modify is detected the whole iterator is started over again. + */ +struct dma_fence *dma_resv_walk_unlocked(struct dma_resv *obj, + struct dma_resv_cursor *cursor, + bool all_fences, bool first) +{ + struct dma_fence *fence = NULL; + + do { + /* Drop the reference from the previous round */ + dma_fence_put(fence); + + cursor->is_first = first; + if (first) { + cursor->seq = read_seqcount_begin(&obj->seq); + cursor->index = -1; + cursor->fences = dma_resv_shared_list(obj); + cursor->is_exclusive = true; + + fence = dma_resv_excl_fence(obj); + if (fence && test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, + &fence->flags)) + fence = NULL; + } else { + fence = NULL; + } + + if (fence) { + fence = dma_fence_get_rcu(fence); + } else if (all_fences && cursor->fences) { + struct dma_resv_list *fences = cursor->fences; + + cursor->is_exclusive = false; + while (++cursor->index < fences->shared_count) { + fence = rcu_dereference(fences->shared[ + cursor->index]); + if (!test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, + &fence->flags)) + break; + } + if (cursor->index < fences->shared_count) + fence = dma_fence_get_rcu(fence); + else + fence = NULL; + } + + /* For the eventually next round */ + first = true; + } while (read_seqcount_retry(&obj->seq, cursor->seq)); + + return fence; +} +EXPORT_SYMBOL_GPL(dma_resv_walk_unlocked); + /** * dma_resv_copy_fences - Copy all fences from src to dst. * @dst: the destination reservation object diff --git a/include/linux/dma-resv.h b/include/linux/dma-resv.h index 9100dd3dc21f..f5b91c292ee0 100644 --- a/include/linux/dma-resv.h +++ b/include/linux/dma-resv.h @@ -149,6 +149,39 @@ struct dma_resv { struct dma_resv_list __rcu *fence; }; +/** + * struct dma_resv_cursor - current position into the dma_resv fences + * @seq: sequence number to check + * @index: index into the shared fences + * @shared: the shared fences + * @is_first: true if this is the first returned fence + * @is_exclusive: if the current fence is the exclusive one + */ +struct dma_resv_cursor { + unsigned int seq; + unsigned int index; + struct dma_resv_list *fences; + bool is_first; + bool is_exclusive; +}; + +/** + * dma_resv_for_each_fence_unlocked - fence iterator + * @obj: a dma_resv object pointer + * @cursor: a struct dma_resv_cursor pointer + * @all_fences: true if all fences should be returned + * @fence: the current fence + * + * Iterate over the fences in a struct dma_resv object without holding the + * dma_resv::lock. The RCU read side lock must be hold when using this, but can + * be dropped and re-taken as necessary inside the loop. @all_fences controls + * if the shared fences are returned as well. + */ +#define dma_resv_for_each_fence_unlocked(obj, cursor, all_fences, fence) \ + for (fence = dma_resv_walk_unlocked(obj, cursor, all_fences, true); \ + fence; dma_fence_put(fence), \ + fence = dma_resv_walk_unlocked(obj, cursor, all_fences, false)) + #define dma_resv_held(obj) lockdep_is_held(&(obj)->lock.base) #define dma_resv_assert_held(obj) lockdep_assert_held(&(obj)->lock.base) @@ -366,6 +399,9 @@ void dma_resv_fini(struct dma_resv *obj); int dma_resv_reserve_shared(struct dma_resv *obj, unsigned int num_fences); void dma_resv_add_shared_fence(struct dma_resv *obj, struct dma_fence *fence); void dma_resv_add_excl_fence(struct dma_resv *obj, struct dma_fence *fence); +struct dma_fence *dma_resv_walk_unlocked(struct dma_resv *obj, + struct dma_resv_cursor *cursor, + bool first, bool all_fences); int dma_resv_get_fences(struct dma_resv *obj, struct dma_fence **pfence_excl, unsigned *pshared_count, struct dma_fence ***pshared); int dma_resv_copy_fences(struct dma_resv *dst, struct dma_resv *src);